In the process of weaving yarns, warp beams containing the warp yarns are placed on a slasher machine where the yarn is given a protective coat of size to hold the threads together and prevent the threads from being chafed during the weaving process. Water has traditionally been the dissolving medium in which size chemicals are dispersed to aid in uniform application. Typically, a ten percent add-on weight of size is desirable and a solution of ten percent solids (sizing) and ninety percent water has been utilized. However, this requires that nine pounds of water for every one pound of size be squeezed and dried out of the yarns requiring a considerable amount of energy.
In conventional processes, the warps are passed under an immersion roll and totally immersed in the sizing solution in the slasher box. Subsequently, the warps pass between a pair of rolls where one to two thousand pounds of pressure is applied to the warps to press in the size and remove some of the water before drying. Attempts to further minimize drying and energy requirements have included the development of high pressure slasher boxes wherein a more concentrated size solution is applied to the warps and hence less water. Concentrated solutions of up to seventeen percent have been utilized. Pressure rolls operating with pressures of up to twenty thousand pounds are utilized to squeeze out the excess size and water. The normal add-on weight of size is applied to the yarns while less evaporative drying is required due to the presence of less water in the sizing solution and subsequent pickup by the warps. However, considerable amounts of energy is still required in drying.
Drying normally includes passing the warps through a hot air blower box and/or passing the warps over heated dry cans. The warps normally become bonded together to form warp sheets when passing over the heated rolls requiring that the sheets be passed through leasing apparatus to separate the warps for weaving. However, damage to the yarn fibers often results as the warps are torn apart during the leasing process.
Engraved, etched or embossed rolls have been, for example, conventionally used in finishing as metering or applicator rolls and the like, as well as in non-wovens for binder application in the print bonding of fibrous webs.